Tertiary alcohols reaction with, phosgene

Reactions. As with other tertiary alcohols, esterification with carboxylic acids is difficult and esters are prepared with anhydrides (181), acid chlorides (182), or ketene (183). Ca.rba.mic esters may be prepared by treatment with an isocyanate (184) or with phosgene followed by ammonia or an amine (185). 

Although numerous methods are known for the synthesis of carbamates of primary and secondary alcohols, they are not satisfactory for the preparation of carbamates of tertiary alcohols /-Butyl carbamate was first obtained by reaction of sodium /-butoxide with phosgene and tbionyl chloride at —60°, followed by reaction with concentrated aqueous ammonia, the overall yield was less than 20%. This procedure, however, was found to be unsuitable for the preparation of carbamates of other tertiary alcohols. Carbamates have been prepared by the... 

When the reaction is realized with a large excess of RMgX and CO2 gas, tertiary alcohols with three identical groups are isolated after hydrolysis. Such alcohols may also be obtained with dialkylcarbonates or phosgene. 

PROBLEM 18.13 Dialkyl carbonates can be made from the reaction of phosgene with alcohols. These carbonates are converted into tertiary alcohols with three identical R groups on reaction with three equivalents of a Grignard reagent or an organolithium reagent. Provide mechanisms for the formation of carbonates and tertiary alcohols in these reactions. 

Novel functionalized peroxides which may be used as UPR curing agents as well as initiators for polymerization reactions and as monomers for polymerizations to form peroxy-containing polymers were elaborated [162]. Initiators may be prepared by reacting hydroxy-containing tertiary hydroperoxides with diacid halides, dichloroformates, phosgene, diisocyanates, acid anhydrides and lactones to form the functionalized peroxides. These reaction products may be further reacted, if desired, with dialcohols, diamines, aminoalcohols, epoxides, epoxy alcohols, epoxy amines, diacid halides, dichloroformates and diisocyanates to form additional fimctionalized peroxides. The use of monoperoxyoxalates of the structure (Scheme 24) as initiators... 

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